HFE/MET/M1 -  Wind Speed data contain offset due to induced voltage

The marine model of the RM Young wind sensor needs twisted pair shielded cable.  The 
manufacturer did not originally supply the pigtail with twisted pair shielded cable.  Use of 
twisted pair shielded cable for the rest of the cable run to the logger was also not 
specified.  This caused an induced voltage in the wind speed line from the wind direction 
excitation.  The induced voltage varied from sensor to sensor and probably changed anytime 
the cable was replaced or parts of the wind sensor were repaired or replaced. The induced 
voltage has been seen to vary from 0.15 m/s to as much as 1.08 m/s.

• wind_spd_arith_max
• Vector-averaged Wind Speed(wind_spd_vec_avg)
• wind_spd_arith_min
• wind_spd_arith_sd
• Wind speed, lower, 1-min avg(wind_spd_arith_avg)

HFE/MET/M1 - Intermittent barometer failure

Intermittent barometer failure occurred throughout the deployment.  We were unable to 
pinpoint the cause of the failure.  Typically one or two minutes of missing data occurred 
every few days.

Since pressure data is typically invariant over 1 minute, linear interpolation should be 
fine to fill in missing data.

• Atmospheric pressure(atmos_pressure)

HFE/MET/M1 - Intermittent PWD data

The Present Weather Detector had intermittent missing values throughout this deployment.  
Missing values occurred almost everyday, usually just one or two minutes per day.

• pwd_cumul_snow
• Average 10 min visibility(pwd_avg_vis_10_min)
• pwd_pw_code_15_min
• pwd_id
• pwd_err_code
• Average 1 min visibility(pwd_avg_vis_1_min)
• pwd_pw_code_1_hr
• pwd_avg_H2O_int_1_min
• pwd_pw_code_inst
• pwd_cumul_water

HFE/MET/M1 - ORG Measuring Ice Crystals or Fog

The ORG was measuring consistent values for long periods of time.  Typically this is 
indicative of fog, ice crystals in the air or poor performance of the lens heaters.

• precip_rate_sd
• Rain, surface, 1-min avg(precip_rate_mean)
• precip_rate_max
• precip_rate_min

HFE/MET/M1 - Induced voltage on wind speed sensor cable

The cable for the wind monitor is not a twisted pair shielded cable.  This caused an 
induced voltage on the wind sensor wires from the wind direction measurement excitation 
voltage.  A small offset is added into the wind speeds.  This value varies.  Most frequently 
the values of 0.49, 0.588 and 0.686 m/s were added into the wind speed.  On 11/27/2008 the 
value jumped to 0.98 m/s for most of the day.

• wind_spd_arith_max
• Vector-averaged Wind Speed(wind_spd_vec_avg)
• wind_spd_arith_min
• wind_spd_arith_sd
• Wind speed, lower, 1-min avg(wind_spd_arith_avg)

HFE/MET/M1 - Reprocess: ORG Data has very small rainrate values

The ORG data is collected via analog signal and not digital.  Therefore, we continuously 
collect data even when no rain is occurring.  We also capture small events such as leaves, 
large bugs, dust, etc blowing through the measurement path.  Because this discrete event 
occurs quickly the value is usually captured for 1 or 2 seconds.  This value is then 
averaged to the minute producing rainrate on the order of .009 mm/hr or less.  

These values are not indicative of rain and should be removed from the record or summing 
over long periods can bias the climate record.  We will reprocess the data to remove these 
small values.

• precip_rate_sd
• Rain, surface, 1-min avg(precip_rate_mean)
• precip_rate_max
• precip_rate_min